Method for refining fatty acids



O 'derivatives of hydrocarbons such as a wax oxida- Patented Apr. 28, 1936 PATNT OFFICE aosaerr -mz'mon Fon asmmc vm'r'rr Acms Hans avesterazi, Elizabeth, N. J., mimo: t

Standard Oil Development Company, a corporation of Delaware Application December 1, 12 333,-Serial No. 700,458 10 mam. (ci. 260-122) z i This invention relates to an improved method for refining fatty acids, and more particularly to means for separatlng fatty acids from other Oxygen containing products of the limited Oxidation -of paraflins, especially of high molecular weight parafiins such as paraflin Wax. Petrolatum, and petroleum white oils. t

The use of relatively large amounts of phos-, phoric acid to separate Oxygen containing hydrocarbon. derivatives from their solution in hydro- H. E. Buc. It has now been found that by the use of relatively much small'er amounts of phosphoric acid, or of other mineral acids such as sulfuric'acid, various Oxygen containing organic compounds can be separated from admixture with fatty acids as in the products lobtained by the limited Oxidation of hydrocarbons. The drawing is a diagrammatic representation of' .a suitable fiow plan for applying the process of the present invention to the refining ofv fatty acids obtained by partial oxidation of parafiins;

Referringv to the drawing, a mixture of Oxygen tion product containing fatty acids and other oxygenated organiccompounds such as la'ctones, alcohols, esters and the like is mixed with a lsuitable lamount of naphtha and is then passed in countercurrent' contact with a suitable mineral acid such as concentrated phosphoric acid.v The phosphoric acid removes preferentially the oxygenated, products. other than fatty acids from the naphtha solution together with a small amount of fatty acids. 'This phosphoric acid extract may then be washed with a small amount of naphtha. The resulting' naphtha'solution of fatty acids may be -added to' the rafiinate. The naphtha. solution (raflinate) is then washed with water to remove any small' amount of phosphoric acid contained therein, The'fatty acids may'then be separated from the naphtha. solution by any suitable method, for example, the naphtha may be removed by distillation and recycled. If'the crude Oxidation products Originally used contained unoxidized high boiling hydrocarbons, the fatty acids may be separated from these by suit able saponification, water extractionand reacidulationsteps as are commonly-praticed in this art. t.

The vextract consisting primarily of hydroxy fatty acids may be. separated from the phosphorlc acid by dilution with a 'small amount of water. On standing the upper layer of 'organic materials separates from. a lower aqueous layer of phosphoric acid. The upper layer may be withdrawn as about and washed with water to remove resldual traces of phosphoric acid. The diluted phosph'oric acid .from the separator with, if desired, the added' wash water is then reconcentrated, by suitable methods; s'uch as by removal of waterin a vacuum still. The ccncentrated acid may suitably be recycled. The aqueous distillate may-contain ar small amount of oxygenated-rganic compounds which were soiuble in -the diluted phosphoric acid.

This distiliate is condensed and any water insolu'- ble organic material may be separated as an upper layer from the conde'nsate. The aqueous distillate may also contain a small amount of' water soiuble organic compounds and may .suitabl be reused'to' dilute the phosphoric acid ex- The mineral acid used for the extraction should tract, or the water soiuble organic compound 'may be concentrated and is preferably of about to or 'strength The amount Ofphosphoric acid used will vary according to the'content of the processmay also be conducted with any of fatty acidand other oxygenated products in the 25 volume much smallerf than that .of the material suchl steps in parallel flow-or with 'batch agitators. A number of agitators mayV also be used i-n series for any one step. The invention is i'urther illustrated by the following. example:

' Exampli Paraifl'n Wax is oxidized to an acid value of about 50 by blowingwith air at to C. in the presence of a suitable Oxidation catalyst such nese soap. The crude product is saponified with aqueous potassium 'hydroxide for several hours at the boiling point of the solution. On cooling, the solution is made acid'with dilute hydrochloric and 20.30 grams of the liberated acids are taken up in two volumes, of naphtha. The naphtha solution 1A% sodium carbonate and 1/2% mangais then shaken thoroughly with 1/20 volume of 85% phosphoric acid. On standing, the phosphoric acid settles out and removes most of the hydroxy acids from the naphtha. solution. When the phosphoric acid layer hasbeendrawnloif. it is shaken up with fresh naphtha. several times to extract from it any vfatty acids which have been mechanically occluded by the acid. The phosphoric acid layer is finally diluted with suflicient water to give about 60 to '70% strength phosphoric acid based only on the water and phosphoric acid content of the mixture. Naphtha or some other low boiling solvent for the hydroxy acids is also added and the liberated hydroxy acids are separated as an upper layer. The extract is washed free of inorganic acids and then dried. The' solvent is then removed at as low a temperature as possible. There is obtained as the residue of this distillation 159.5 grams of an oxygenated product consisting largely of hydroxy fatty acids. This product also contains asubstantial proportion of esters and other oxidation products dei agents suitable for use even in hard water, and

similar in many respects to sulfated castor oil acids.

Mineral acids may also be used as described above for the treatment of the acid fraction obtained bysaponification of the crude oxygenation product and re-acidification of the resulting soaps.

The refined fatty acids secured by this invention are greatly improved in color, odor and stability. and may be used to prepare soaps which aremuch Superior to those obtained from the crude fatty acids obtained by ordinary saponification and re-acidulation of partially oxidized parafiln Wax.

The use of sulfuric acid for refining oxidized wax acid is illustrated by the following example:

Emample 2 250 cc. of a crude oxidation product of parafiln wax prepared as described in Example 1 is dissolved in '750 cc. of a 56 Baun'i petroleum naphtha which is inert to concentrated sulfuric acid. To 200 cc. of this solution are added with stirring 5 cc. of strength sulfuric acid. The mixture is allowed to stand for about an hour and separates into two layers. an upper layer of the naphtha solution and a lower layer containing substantially all the sulfuric acid and 20 cc. of a hydroxy acid extract. Refined fatty acids may then be recovered from the naphtha solution by any suitable method, such as that described in the above example. Unsulfated oxy organic compoundsl may be secured by diluting the acid extract with water. A mild hydrolysis may be desirable for recovery of all vthe extract'ed oxy compounds. Very good sulfated detergents may be prepared, however, by adding an excess of strength sulfuric acid directly to the total sulfuric acid extract, heating the mixture to 90,/to 95 C. for about two hours, and then neutralizing with caustic soda or sodiumcarbonate. The resulting soaps are at least equivalent to sulfated castor oil acid soaps for use in hard water.

This invention may also be applied to the crude wax oxidation products or to other fractions thereof obtained by distillation or extraction with other solvents such as lower aliphatic alcohols. For example, methyl alcohol containing 5 to 10% of water may vbe used to extract substantially all oxygenated products from the unoxidized wax and the extract may be refined as described herein.

This invention is not to be limited to any specific examples which have been presented' herein solely for purpose of illustration but is limited only by the following claims in which it is desired to claim all novelty insofar as the prior art permits.

I claim:

1. Method for separating hydroxy aliphatic acids from fatty acids comprising contacting a mixture of said fatty acids and said hydroxy acids with concentrated phosphoric acid in a volume substantially less than that of said mixture, permitting the separation of layers and separately withdrawing a resulting layer containing mainly phosphoric acid and said hydroxy' acids from a remaining layer containing said fatty acids.

2. Method according to claim A1 in which the mixture of fatty acids and hydroxy -aliphatic acids consists of a solution' of said acids in naphtha.

3. Method according to claim 1 in which said mixture of organic acids is a product of the limited oxidation of parafiin hydrocarbons.

4. Method according to claim l1 in wich said mixture of 'organic acids is a product of the oxidation of paraffin wax at to 16Q C. with oxy- 3 gen to an acid value of about 50.

5. Method for separating fatty acids from other oxygenated products comprising dissolving partially oxidized wax in petroleum naphtha and selectively extracting products more oxidized than fatty acids therefroml with concentrated phosphoric acid in a volume substantially less than that of said partially oxidized Wax.

6. Method for refining crude fatty acids produced by partial oxidation of paraffin hydrocarbons comprising selectively extracting other oxy organic compounds from said crude acids with concentrated phosphoric acid in a volume substantially less than that of said crude acids.

7. Method according to claim 6 in which the volume of said phosphoric acid is from about T16 to 1/40 of the volume of said crude fatty acids.

8. Method according to claim 6 in which said crude fatty acids are obtained by saponification of the partial oxidation product.

9. Method for separating fatty acids from other oxygenated products comprising separating oxygenated compounds from partially oxidized paraffin Wax by means of a selective solvent and selectively extracting products more oxidized than fatty acids from said separated oxygenated compounds with concentrated phosphoric acid in a volume substantially less than that of Asaid oxygenated compounds.

10. Method according to claim 9 in which said selective solvent is aqueous methyl alcohol containing 5 to 10% of water.

HANS G. vEs'rE'RDAL. 

